Aromatic polyamides from n,n&#39;-diphenyl diamines



United States Patent 3,418,275 AROMATIC POLYAMIDES FROM N,N'-DIPHENYLDIAMINES Curtis Wayne Stephens, Longwood, Wilmington, Del., assignor toE. I. du Pont de Nemours and Company, Wilmington, Del., a corporation ofDelaware No Drawing. Original application Nov. 8, 1962, Ser. N0.236,393. Divided and this application July 6, 1966, Ser. No. 563,051

4 Claims. (Cl. 260-47) This application is a division of my applicationSer. No. 236,393, filed Nov. 8, 1962, now US. Patent 3,296,201.

This invention relates to novel and useful compositions of matter. Moreparticularly, it relates to a novel group of high molecular weightfilmand fiber-forming nitrogencontaining condensation polymerscharacterized by a high degree of stability, to a process for preparingthem and to shaped articles prepared therefrom.

The broad class of nitrogen-containing condensation polymers in whichnitrogen atoms are included as integral parts of the polymeric chain hasbeen recognized for many years and several members of this class ofpolymeric materials have achieved a notable degree of commercial successand public acceptance. The currently available nitrogen-containingcondensation polymers are found to be excellently adapted for use inmany areas of application. Almost without exception, they arecharacterized by the presence of secondary amido nitrogen atoms (to eachof which is bonded a hydrogen atom). It has long been recognized bypolymer chemists that the replacement of these hydrogen atoms bymonovalent organic radicals leads to the formation of polymericmaterials which have lower melting points and more rubbery propertiesthan the unsubstituted polymers. For this reason, polymer chemists have,in general, tended to avoid the preparation of such polymers which lackthe capacity for hydro gen bonding.

One object of this invention is to provide high molecular Weightnitrogen-containing linear condensation polymers which are characterizedby a high degree of thermal and hydrolytic stability and which may beformed into tough, pliable shaped articles.

Another object of this invention is to provide a process for thepreparation of high molecular Weight nitrogen containing condensationpolymers by the condensation of weakly basic amino groups with acidhalides, without the necessity of acid acceptors.

A further object of this invention is to provide such condensationpolymers which, in the form of fibers, may be utilized in thepreparation of fabrics which are characterized by being trulywash-wearable. By wash-wear performance is meant the ability to bewashed and then worn without the need of ironing. Certain currentlyavailable polyesters, such as poly(ethylene terephthalate), have madepossible the first approach to such fabrics, but their application inarticles of commerce has resulted in fabrics which, While exhibitingappreciably better washwear performance than those composed of naturalfibers, normally require at least touch-up ironing.

Other objects will be apparent from the specification and examples tofollow.

In accordance with these objects, there is provided a novel class ofhigh molecular weight filmand fiberforming linear condensation polymerswhich contain intralinear nitrogen atoms bearing a lateral aromaticradical, which polymers are characterized by consisting essentially ofrecurring structural units of one of the following types:

3,418,275 Patented Dec. 24, 1968 wherein R represents a monovalentaromatic radical; Ar represents a divalent aromatic radical, Rrepresents a divalent aromatic radical and n is a cardinal number notgreater than 1. The present invention also provides for preparing saidpolymers which comprises reacting a carbonyl halide function and asecondary amino function, both substituents on said secondary aminofunction being aromatic radicals, at a temperature Within the range of50400 C., the by-product hydrogen halide being continuously removed fromsaid reaction by volatilization. In all instances the polymers arecharacterized by the presence in the polymeric chain of amide-typelinking units wherein the nitrogen atoms are substituted by monovalentaromatic radicals.

The presence of bulky aromatic lateral substituents on the polymericchain surprisingly does not result in a lack of crystallizability in thepolymeric compositions. Although it has been recognized for many yearsthat increasing substitution of the amido nitrogen atoms in aliphaticpolyamides results in a diminution of useful properties, it is noted inthe series of polymers which C011- stitute this invention that highlyuseful polymeric compositions result from wholly aromatic polymerscontaining aromatic substituents on the amido nitrogen atoms.

By the expression consisting essentially of is meant that no more thanabout 10% of the total polymeric structure may consist of units otherthan those described herein. The molecular weights of the polymers ofthis invention may be varied widely, but it is preferred that thepolymers have a molecular weight of at least about 10,- 000 and, moreespecially, of at least about 25,000 or higher.

Further in accordance with the above mentioned objects, there areprovided shaped articles comprising the polymers of this invention. Sucharticles may consist entirely of the instant polymers, e.g., films andfilaments, or only partly so, e.g., coated wire and laminated sheets.Preferred are those articles consisting entirely of the polymers of thisinvention. Particularly preferred are those articles which have thetransverse dimension (diameter or thickness) greatly exceeded by thelongitudinal dimension, in which category are included films, fibers,filaments, strand, pellicles, and the like. These shaped articles may bereadily prepared either from solutions of the polymers in suitablesolvents, by melt shaping, or by other recognized procedures, as will befurther described hereinafter. The shaped articles may be oriented byattenuation or drawing, by which process their properties areappreciably improved.

The polymers of this invention may be prepared in accordance with asolution technique, by which the polymer-forming reactant or mixture ofreactants is dissolved in a suitable solvent and the solution ismaintained at a temperature such that the condensation reaction proceedsat a reasonable rate. Temperatures in the range of 50 to 400 C. arenormally satisfactory, and the desired temperature may frequently beobtained by choosing a solvent such that its temperature of reflux iswithin the desired range. Preparation of the polymers in solution isreadily elfected, particularly since no acid acceptor is required.

3 Isolation of the polymeric material is effected by standardprocedures.

The polymer-forming reaction by which the polymers of the presentinvention are prepared normally involves the condensation of amultiplicity of difunctional organic molecules, each individualcondensation being effected by the reaction of a substituted amino groupwith an appropriate acid group, or a derivative thereof whether thatlatter group be a carbonyl halide group to produce a polyamide, achloroformate or carbonate ester to produce a polyurethane, or phosgeneor a carbamic acid derivative to produce a polyurea. Where a diamineconstitutes one difunctional reactant, a wholly aromatic disecondarydiamine is employed. Diamines of this type have long been recognized asbeing unstable to oxidation, showing evidences of degradation even uponexposure to air. They have also been recognized as possessing extremelylow base strength, forming readily hydrolyzed salts even with strongacids. It is therefore surprising that such diamines can be successfullyutilized as polymer-forming reactants, and particularly surprising thatthe resulting polymers are of high molecular weight, oxidatively andhydrolytically stable, and capable of the formation of tough andflexible shaped articles.

In certain instances, where a polyurethane is the desired product, thepolymer-forming reaction may involve, at each point of condensation, thereaction between a nitrogen-substituted carbamic acid group with anappropriate hydroxyl group. Among suitable acid components, the freeacids may be employed where they are available and stable, or thevarious conventional acid derivatives may be utilized, as the aliphaticor aromatic esters or the sulphur analog thereof, the anhydrides, theamides, the acid halides, and the like. Generally, it is preferred toemploy the acid halides, and it is with this reactive acid derivativethat the remainder of this discussion will be concerned.

It will be apparent that, when a linear high molecular weight polymericmaterial is to be provided, a reaction between difunctional startingmaterials is required. Such starting materials may include within' onemolecule the two types of necessary functional groups (as, e.g., anitrogen-substituted amino function and an acid chloride function) inwhich case the polymerization proceeds by a process ofself-condensation. Alternatively, the starting materials may contain twofunctional groups of the same type in any one molecule, in which casetwo types of reactant are required (as e.g., one reactant, each moleculeof which contains two nitrogen-substituted amino functions, beingcondensed with a second reactant, each molecule of which contains twoacid chloride groupings).

The preferred process of this invention comprises the elimination of theelements of a hydrogen halide from between equimolar quantities of anactive-hydrogen function and a carbonyl halide function, as follows:

-H-X HB -1[B BK wherein X represents a halogen, preferably chlorine, andB represents a diarylamino radical or, when COX is attached to nitrogen,an aryloxy radical. This process is facilitated by the application ofheat, and by permitting the hyrogen halide to escape from the reactionzone by volatilization, and does not employ the presence of anacidacceptor such as an organic or inorganic base in order to effectsubstantially complete conversion of the reactants. Condensations ofthis type, when carried out with HE compounds in which B is a nitrogenatom to which is attached one or two hydrocarbon radicals, one or moreof the latter being saturated, require the presence of at least oneequivalent of a base for each mole of hydrogen halide formed. This isthought due to the binding of the hydrogen halide to the amino groupsthrough salt-formathereby making the amine function i ert to acylationby the halocarbonyl function. The acid-acceptors are believed to preventthis salt-formation by preferentially binding the hydrogen halide. Thediaryl amine-type HB functions of this invention do not employ thepresence of an acid-acceptor, and accordingly, the halide is free toescape from the polymerization zone by volatilization.

In the above formulae Ar has been defined as a divalent aromaticradical. It may represent mor p-phenylene, 1,3-naphthylene,1,4-naphthylene, 1,5-naphthylene, 2,6-naphthylene, p,p-biphenylene,m,m-biphenylene, or the like, or a radical having two or more aromaticnuclei linked by a methylene group, a substituted methylene group, asulfone group, an ether linkage, or other small divalent linking unit,as bis(p-phenylene)methane, bis (m-phenylene)methane, 2,2bis(p-phenylene)propane, bis(p-phenylene)sulfone, bis(p-phenylene)ether, and the like. Any of the aromatic nuclei in the above listing mayadditionally bear one or more nuclear substituents, such as halogenatoms, lower alkyl groups, and the like, which are non-reactive underthe conditions used to prepare the polyamides. The preferred divalentaromatic radicals are p-phenylene, m-phenylene, p,p-biphenylene,bis(p-phenylene) ether, bis(p-phenylene) sulfone, and their nuclearlychlorinated derivatives. Of particular interest among these preferredradicals are p-phenylene, m-phenylene, and p,p'-biphenylene. R is adivalent aromatic radical selected from among those defined above forAr. When the subscript n in Formula 1 is zero, the term (R) is acarbon-to-carbon bond. The monovalent aromatic radical R is preferablyphenyl, but may also represent a substituted phenyl having up to fivesubstituents selected from the group consisting of lower alkyl, halogen,preferably chlorine, or p-phenyl.

The polymers of this invention possess a number of attractive and usefulphysical properties. In the first place, they are highly stable toprolonged exposure to heat. Shaped articles comprising these polymersretain a high percentage of their original strength when subjected totemperatures in excess of 200 C. for prolonged periods of time.Additionally, the polymers exhibit a high degree of resistance tohydrolytic media, including both hot aqueous acids or bases. They arenot affected by ammonia or amines. The polymers resist combustion, andpossess good electrical properties. They are soluble in a wide varietyof solvents, and can generally be crystallized. The inherent viscositiesof these polymers ordinarily exceed about 0.35, thereby rendering themsuitable for the preparation of shaped articles. These and othernoteworthy properties will be further apparent from the discussion andexamples which follow.

All of the polymers of this invention are characterized by high levelsof heat and flame resistance and are suitable for conversion to shapedarticles resistant to bydrolysis. Their properties may perhaps best beconsidered with respect to the specific polymer types, i.e., polyamide,polyurethane, and polyurea.

Polyamides.As has been pointed out above, the polyamides of thisinvention are derived either from N,N'- disubstituted aromatic diaminesand amide-forming derivatives of aromatic dicarboxylic acids or oxalicacid, or from monomeric organic compounds which contain in each moleculeboth an acid function and an aromatic secondary amino group. Like otherpolymers of this invention, the polyamides are characterized by a highde gree of thermal and hydrolytic stability, by high melting points andby the ability to form tough films and crystalline oriented fibers.

The polyamides may be prepared by the condensation of an aromaticdiamine which bears an aromatic substituent on each of the aminonitrogen atoms with the acid halide of an aromatic dicarboxylic acid orwith oxalyl chloride, or by the self-condensation of an aromatic organiccomposition, each molecule of which contains a carboxylic acid halidegroup and a single amino group which bears an aromatic substituent. V

Among suitable aromatic diamines where each of the amino nitrogen atomsis a secondary amino group are those having the formula:

wherein Ar is a divalent aromatic radical of the types previouslydescribed, preferably hydrocarbon or halohydrocarbon comprising one ortwo phenylene radicals, and R is a monovalent aromatic radical aspreviously defined preferably a phenyl group. Thus, among diamineswithin the scope of this invention may be named the following:N.N'-diphenyl-p-phenylenediamine, N.N diphenyl-mphenylenediamine, N.N'diphenyl 1,4 naphthylenediamine, N-N-diphenyl 1,3 naphthylenediamine,N,N diphenyl-2,6-naphthylenediamine, N,N diphenyl 1,5-naphthylenediamine, N,l-I-diphenylbenzidine, and the like, which may,additionally, bear nuclear substituents of the non-amide forming type.

The polyamides are prepared by the condensation of diamines of the abovetypes with amide-forming derrivatives of dicarboxylic acids. The acidhalides are generally employed, and the chlorides are normallypreferred. These acid derivatives have the following structures:

wherein X is a halogen atom and wherein R is a divalent aromatic radicalof the type described above in the definition of the Ar group preferablyhydrocarbon comprising one or two carbocyclic aromatic radicals When thesubscript n is zero, the term (R designates a carbon-tocarbon bond.Thus, among useful dicarboxylic acid derivatives may be named thefollowing: oxalylchloride, isophthaloyl chloride, terephthaloylchloride, 1,3 -naphthalene dicarbonyl chloride, 1,4-naphthalenedicarbonyl chloride, p,p'-biphenyl dicarbonyl chloride, the acidchloride of 4,4-dicarboxyldiphenyl ether, and other comparable acidchlorides derived from aromatic .dicarboxylic acids. Also useful are theacid bromides of these dicarboxylic acid.

The preparation of high molecular weight polyamides may be eifected bydissolving equivalent amounts of the diamine and the diacid halide in asuitable solvent having a boiling point in the range of 50-350 C. Uponmaintaining the solution at the temperature of reflux for a period of5-20 hours, a high molecular weight polymer is produced. The hydrogenchloride formed as a byproduct of the condensation is volatilized underthe conditions of reaction. The polymeric product may normally beisolated by cooling the reaction mixture, and filtering the precipitatedpolymer. In those instances where the polymer remains soluble in thecooled reaction mixture, it may be isolated by dilution of the mixturewith a suitable non-solvent. Suitable solvents for effecting solutionpolymerization are generally chosen from the class of hydrocarbons andchlorinated hydrocarbons, as chlorobenzene, o-dichlorobenzene, toluene,xylene, tetrachloroethane, and the like. Particularly preferred iso-dichlorobenzene, whose temperature of reflux permits rapidpolycondensation. By suitable modification of the above procedures,polyamide forming monomeric materials may be self-condensed to formpolymeric compositions.

The polyamides prepared by the above techniques may be utilized directlyin the formation of shaped articles, which may be prepared fromsolutions of the polymers in suitable solvents, by melt shaping, or bywet-spinning techniques. Suitable solvents include methylene chloride,N,N-dimethylformamide, 1,1,2-trichloroethane, mixtures of1,1,2-trichloroethane and trifiuoroacetic acid, and the like, andspinning solutions normally contain between 12% and 25% of the polymer.Such solutions have vis cosities within the range of 100-300 poises atthe spinning temperature. The dry-spinning of these polyamides may beaccomplished in accordance with accepted procedures, as will be shown bythe examples to follow. The resulting fibers may be drawn 23X or more attemperatures at or near their second order transition temperatures,producing oriented, crystalline yarns. Drawing in steam may also beeffected.

These N-aryl polyamides generally have greater resistance to hydrolysis,and to thermal degradation in the presence or absence of oxygen than isexhibited by the analogous N-hydrogen or N-alkyl polyamides. Theseanalogues differ structurally from the products of this invention onlyin the presence of a hydrogen atom or alkyl group substituent in placeof the lateral aryl group on each nitrogen atom. Such unsubstituted orN-alkyl substituted aromatic polyamides are described in Canadian Patent637,614. The N-aryl polyamides of the present invention cannot be madein the high molecular weight range required for making useful fibers andfilms by the processes known in the art for their above-mentionedanalogues.

The following examples ilustrate the preparation and shaping of thepolyamides of this invention, but are not to be construed as limitingthe scope of the invention in any way. Inherent viscosities aredetermined in accordance with the following formula:

77 & 7rel The relative viscosity (1 may be determined by dividing theflow time in a capillary viscometer of a dilute solution of the polymerby the flow time for the pure solvent. The concentration (c) is 0.5 gramof polymer per ml. of solution, and the measurements are made at atemperature of 30 C. The determinations are made in concentratedsulfuric acid.

EXAMPLE I Commercial grade N,N-diphenyl-p-phenylene diamine is purifiedby distillation, collecting the fraction which boils at a temperature of240 C. at a pressure of 0.5 mm., followed by three recrystallations frommethylene chloride. To milliliters of dry o-dichlorobenzene are added7.00 grams of the purified diamine and 5.48 grams of terephthaloylchloride. The mixture is heated to the temperature of reflux while thesolution is stirred, and nitrogen is bubbled through for a period of 15hours. The product is removed by filtration after cooling the reactionmixture, and is slurried with acetone, filtered, and dried for 2 hoursin an evacuated oven at a temperature of 100 C. The resulting product isfound to exhibit an inherent viscosity of 1.49. Further polymerizationis effected by heating the dry solid for a period of two hours at atemperature of 321 C. under reduced pressure. The inherent viscosity isthereby raised to 2.35. The polymer exhibits a melt temperature of 390C., and has a linear structure comprising the following repeat unit:

The polyamide derived from N,N'-diphenyl-p-phenylene diamine andterephthaloyl chloride (prepared as described in the preceding example),having an inherent viscosity of about 2.0 is dissolved in a solventmixture comprising three parts of 1,1,2-trichloroethane and one part oftrifluoro acetic acid to the extent of 14% solids. Fibers are dry spunfrom this solution through a spinneret having five holes of 0.005 inchdiameter. The spin neret is maintained at a temperature of 59 C., andthe air in the spinning cell is maintained at a temperature of C. Theyarn produced is wound up at a speed of 128 y.p.m. The fibers are drawnin steam at about 12 psi. or over a hot plate at a temperature of 250 C.Drawing X in steam produces a crystalline yarn. The yarn exhibits atenacity/e1ongation/modulus ratio of 2.7/ 3.6/98. It retains 95% of itstenacity after 65 hours of reflux with 10% sulfuric acid, and 59% of itstenacity after 65 hours of reflux with 10% sodium hydroxide solution.

EXAMPLE III Tcr a three-necked round-bottom flask equipped with astirrer, a nitrogen inlet, and a reflux condenser are added 28.00 grams(0.108 mol) of N,N-diphenyl-pphenylenediamine (previously purified bytwice distilling and by twice recrystalliziug from methylene chloride),21.91 grams (0.108 mol) of isophthaloyl chloride (previously purified bytwice recrystallizing from hexane) and 500 ml. of dry o-dichlorobenzene.The mixture is heated under nitrogen with stirring at the temperature ofreflux for a period 16 hours. The clear solution which results is foundto gel on cooling to room temperature and is precipitated with acetonein a blender. The product is removed by filtration and dried for 25hours in an evacuated oven at temperatures ranging from about 60 C. toabout 100 C. The low polymer is further powder polymerized for a periodof two hours at a temperature of 256 C. under a reduced pressure. Filmsare pressed at a temperature of 290 C. and a pressure of 4,000 p.s.i.The polymer is found to exhibit a melt temperature of 290 C., has aninherent viscosity of 1.45, and consists of a linear structure havingthe following repeating unit:

The high thermal stability of this polymer may be demonstrated bythermogravimetric analysis. This test is carried out with an ovencontaining a balance on which a test sample may be weighed continuouslythroughout the heating period. The oven is provided with a programmedheat control whereby the temperature within the oven is raised at alinear rate of 5 C. per minute. A sample of powdered polymer Weighingabout 0.010 gram is placed in a platinum crucible having a flat bottomabout 0.25 inch in diameter, the crucible is placed on the balance, anitrogen atmosphere is introduced into the apparatus, the sample isaccurately weighed, the heater is turned on, and the weight of thesample is determined at selected intervals. Under the conditions of thistest, a sample of the poly(N,N-diphenyl-p-phenylenediamineisophthalarnide) loses only of its initial weight when heated to 459 C.Under the similar test conditions, the analogous polyamides in which thenitrogen atoms bear either hydrogen or saturated hydrocarbon groups inplace of phenyl groups [i.e., poly(p-phenylenediamine isophthalamide)and poly(N,N' dirnethyl-pphenylenediamine isophthalamide), which may beprepared as shown in Canadian Patent 637,614] lose a more substantialportion of their initial weight.

The hydrolytic stability of poly(N,N'-diphenyl-pphenylenediamineisophthalamide) is determined by refluxing a suspension of a weighedsample of the powdered polymer (about 0.030 gram) in 20 ml. of 3 normalaqueous sodium hydroxide for 22 hours. The mixture is then cooled andfiltered to isolate undissolved polymer, which is then washed withwater, dried, and weighed. In this way it is found that the N,N-diphenylpolyamide of this example has lost 14% of its initial weight. In asimilar test poly(p-phenylenediamine isophthalarnide) and poly(N,N'-dimethyl p phenylenediamine isophthalamide) each losesubstantially more of their initial weight.

8 EXAMPLE IV A three-necked round-bottom flask is equipped with anitrogen inlet, a stirrer, and a reflux condenser. To the flask areadded 14.00 grams (0.054 mol) of N,N'-diphenyl-pphenylenediamine, 2.19-grams (0.011 mol) of isophthaloyl chloride, and 8.77 grams (0.043 mol)of terephthaloyl chloride, together with 250 ml. of o-dichlorobenzene.The mixture is heated at the temperature of reflux for a period of 16hours with stirring. A nitrogen atmosphere is maintained. The mixturegels somewhat upon cooling to room temperature, and the polymer isprecipitated with acetone and isolated by filtration. After washing thepolymer with an additional quantity of acetone, it is dried in anevacuated oven at a temperature of 70 C. Following powder polymerizationof the product for a period of two hours at a temperature of 321 C.under reduced pressure, the polymer is pressed to form a tough film at atemperature of 380 C. The final polymer exhibits an inherent viscosityof 1.80 and a polymer melt temperature of 300 C. This polymer has astructure comprising the following two repeat units in approximately a4:1 ratio distributed randomly along the chain:

and

i agree EXAMPLE V By a procedure analogous with those previouslydescribed, a mixture comprising 14.00 grams (0.054 mol) of freshlypurified N,N'-diphenyl-p-phenylenediamine, 8.77 grams (0.043 mol) ofisophthaloyl chloride, 2.19 grams (0.011 mol) of terephthaloyl chloride,and 250 ml. of dry o-dichlorobenzene is heated at the temperature ofreflux in a nitrogen atmosphere for a period of 17 hours while stirringis maintained. Upon cooling to room temperature, the gelled mixture isprecipitated into hexane in a blender. The product is removed byfiltration and dried overnight in an evacuated oven at a temperature of70 C. The resulting polymer exhibits an inherent viscosity of 0.57, anda polymer melt temperature of 230 C. The polymer has the structure shownin Example IV, but with approximately a 1:4 ratio of terephthaloyl andisophthaloyl units.

EXAMPLE VI To a mixture of 3.50 grams (0.0134 mol) of freshly purifiedN,N'-diphenyl-p-phenylenediamine and 1.38 grams each (0.0067 mol) ofisophthaloyl chloride and terephthaloyl chloride are added 28 ml. ofo-dichlorobenzene. Following heating for a period of 23 hours at thetemperature of reflux in a nitrogen atmosphere, the mixture is cooled toroom temperature. The gel which results is treated with acetone in ablender and the polymer is removed by filtration. The product is washedwith acetone in the blender and isolated by filtration. Drying iseffected by placing the polymeric product in an evacuated oven at atemperature of 70 C. for a period of four hours. The polyamide exhibitsan inherent viscosity of 1.06 and a polymer melt temperature of 247 C.,and has a structure consisting of a l: l ratio of the two units shown inExample IV.

9 EXAMPLE vn By a procedure analogous with those previously described,14.00 grams (0.054 mol) of N,N'diphenyl-mphenylenediamine (previouslypurified by recrystallization from cyclohexane) and 11.00 grams (0.054mol) of terephthaloyl chloride are dissolved in 110 ml. ofchlorobenzene. The mixture is heated at the temperature of reflux for aperiod of 16 hours while stirring is maintained. Upon cooling to roomtemperature, the product is precipitated and is isolated by filtration.The solid is washed with acetone, refiltered, and dried overnight in anevacuated oven at a temperature of 70 C. Further polymerization iseffected by powder polymerization for a period of one hour at atemperature of 283 C. under reduced pressure. The polymer exhibits aninherent viscosity of 0.41, a polymer melt temperature of 384 C., and astructure comprising a linear arrangement of units having the followingformula:

EXAMPLE VIII In a three-necked round-bottom flask equipped with a refluxcondenser, nitrogen inlet, and a stirrer, are placed 14.00 grams (0.054mol) of recrystallized N,N'-diphenylm-phenylenediamine, 11.00 grams(0.054 mol) of freshly recrystallized isophthaloyl chloride, and 110 ml.of dry o-dichlorobenzene. The mixture is heated at the temperature ofreflux with stirring for a period of 16 hours. A nitrogen atmosphere ismaintained during this time. The reaction mixture is cooled to roomtemperature, and the gelled mixture is precipitated with acetone. Theproduct is removed by filtration, washed with acetone, refiltered, anddried overnight in an evacuated oven at a temperature of 70 C. Furtherpolymerization is effected by maintaining the temperature of thepolymeric product at 283 C. for a period of two hours under reducedpressure. The polymer exhibits a melt temperature of 215 C., an inherentviscosity of 0.15, and has a linear structure comprising the followingrepeat unit:

EXAMPLE IX By a procedure analogous with those previously described, around-bottom, three-necked flask equipped with a nitrogen inlet,stirrer, and reflux condenser is charged with 14.00 grams (0.54 mol) ofN,N'-diphenyl-p-phenyl ene-diamine (previously recrystallized threetimes from methylene chloride), 18.46 grams (0.054 mol) of the acidchloride of bis(4-carboxyphenyl) sulfone previously twice recrytsallizedfrom 1,1,2 trichloroethane and distilled), and 250 ml. ofo-dichlorobenzene (distilled from barium oxide and dried over calciumhydride). The mixture is heated to the temperature of reflux withstirring and maintained at that temperature for a period of 16 hourswhile in a nitrogen atmosphere. The mixture partially solidifies uponcooling to room temperature; the solid low molecular weight polymericproduct is separated from the supernatant liquid and stirred with hexanein a blender. The product is removed by filtration and dried overnightin an evacuated oven at a temperature of 70 C. It is further powderpolymerized for a period of two hours at a temperature of 256 C. underreduced pressure. The resulting polymer is found to exhibit an inherentviscosity of 1.71, and a polymer melt temperature of 286 C. Pressedfilms of the polymer are tough and clear. The polymer has a linearstructure comprising the following repeat unit:

0 O I II C EXAMPLE X A mixture comprising 10.82 grams (0.042 mol) ofrecently purified N,N'-diphenyl-p-phenylenediamine, 12.28 grams (0.042mol) of the recrystallized acid chloride of 4,4-dicarboxdiphenyl ether,and 250 ml. of pure dry o-dichlorobenzeue is heated at the temperatureof reflux for a period of 16 hours while stirring and maintaining anitrogen atmosphere. Upon cooling to room temperature, the productprecipitates and is removed by filtration. The solid is washed withhexane, refiltered, and dried overnight in an evacuated oven at atemperature of 70 C. The polymer is further polymerized at a temperatureof 321 C. for a period of two hours under reduced pressure; it is foundto exhibit an inherent viscosity of 0.30, a polymer melt temperature of255 C., and comprises the following repeat unit:

N NC O C EXAMPLE XI In a three-necked, round-bottom flask equipped witha nitrogen inlet, reflux condenser, and stirrer are placed 14.00 grams(0.054 mol) of N,N-diphenyl-p-phenylene diamine and 125 ml. of dryo-dichlorobenzene. To this mixture is added a solution comprising 6.83grams (0.054 mol) of oxalyl chloride dissolved in 125 ml. of dryo-dichlorobenzene. The temperature of the mixture is slowly increaseduntil the temperature of reflux has been reached, and this temperatureis maintained for a period of 23 hours. During the entire period,stirring is maintained, and a nitrogen atmosphere is provided. Uponcooling to room temperature, the polymeric product is precipitated andisolated by filtration. The solid is washed with hexane, refiltered, anddried overnight in an evacuated oven at a temperature of C. A film ispressed at a temperature of 335 C. and a pressure of 8,000 p.s.i. Thepolymer is found to exhibit an inherent viscosity of 0.30, a polymermelt temperature of 335 C., and has the following repeat unit structure:

II II CC EXAMPLE XII in until no further precipitation occurs, and theproduct is removed by filtration and dried under nitrogen. Upon heatingthe product in a solution comprising approximately one gram of thisproduct per 10 ml. of dry o-dichlorobenzene, hydrogen chloride isevolved and a low molecular weight polymer results. This linear polymerexhibits a melt temperature of 350 C. and the following repeat unitstructure:

Polyurethanes.The polyurethanes of this invention are characterized by ahigh degree of thermal and hydrolytic stability, by high melting points,and by an ability to form tough films and filaments. They areparticularly characterized by the ability of fibers comprising thesepolymers to be converted to fabrics which exhibit excellent wash-wearperformance.

These polyurethanes are prepared by the condensation ofN,N-disubstituted aromatic diamines with the hischloroformate ofaromatic dihydroxy compounds, by the condensation of biscarbamyl halidesderived from N,N- disubstituted aromatic diamines with aromaticdihydroxy compounds, or by the self-condensation of the carbamyl halidederivatives of N-substituted amino phenols. The aromatic diamines ofutility, either in the free state or following conversion to thebiscarbamyl halide derivatives, are those having the following formula:

wherein Ar and R have the designations previously given. Among thesediamines may be named the following: N,N- diphenyl-p-phenylenediamine,N,N'-diphenyl-mphenyldiamine, N,N diphenyl 1,4-naphthylenediamine, N,Ndiphenyl-1,3-naphthylenediamine, N,N'-diphenyl- 2,6 naphthylenediamine,N,N'-diphenyl-1,5-naphthylenediamine, N,N'-diphenylbenzidine,N,N-bis(2-naphthyl)- p phenylenedia-mine, p,p-dianilinodiphenylmethane,p,pdianilinodiphenyl ether, p,p-dianilinodiphenyl sulfone, and othersuch N,N-disubstituted aromatic diamines, which may additionally bearone or more nuclear substituents of a non-urethane forming type. If thebicarbamyl halides of these diamines are desired, they may be preparedby reaction of the diamines with phosgene. The aromatic dihydroxycompounds which, either in the free state or in the form of thei.bischloroformate derivatives, are of utility in the formation of thesepolyurethanes are those having the following formula: HO-ArOH where Arhas the designation previously given. Among suitable compounds of thistype may be named the following: resorcinol, hydroquinone,1,3-dihydroxynaphthalene, 1,4- dihydroxynaphthalene, 1,5dihydroxynaphthalene, 2,6- dihydroxynaphthalene, otherdihydroxynaphthalenes, 3,3- dihydroxybiphenyl, 4,4 dihydroxybiphenyl,4,4 isopropylidenebis(2,6 dichlorophenol), 4,4methylenebis(2,6-dichlorophenl), 4,4 dihydroxydiphenyl ether, and othersimilar dihydroxy aromatic compounds which may additionally hear one ormore nuclear substituents of a non-urethane forming type. Suitableself-condensible carbamyl halide derivatives of N-substitutedaminophenols have structures of the following type:

| HOArI Ii J-X wherein Ar, R, and X have the meanings previously given.The compounds may be prepared by the reaction of phosgene or othercarbonyl halide with an aromatic secondary amine, one of the aromaticradicals of which bears a phenolic hydroxyl group. This reaction isnormally effected by dissolving the phenolic secondary amine in asuitable solvent and bubbling phosgene or other carbonyl halide throughthe solution, thus converting the secondary amino group to thecorresponding carbamyl halide Without affecting the phenolic hydroxylgroup.

Suitable secondary amines from which the carbamic acid derivatives maybe prepared are characterized by the presence of two aromaticsubstituents on the amino nitrogen atom, one of which aromaticsubstituents bears a phenolic hydroxyl group. These compositions may beprepared in accordance with any of several synthetic procedures. Thusfor example, they may be prepared by the reaction of an amino phenolwith a phenol under the influence of heat and pressure, by the reactionof an amino phenol with an aromatic amine as described in German PatentNo. 887,345, or by the reaction of a biphenol with an aromatic amine asdescribed in US. Patent No. 2,503,712. Other comparable procedures bywhich an aromatic primary amino group may be converted to a secondaryamino group are also suitable and will be apparent to those skilled inthe art.

The preparation of the compounds is normally effected by bubbling thecarbonyl halide through a solution of the amino phenol in a suitablesolvent at a temperature within the range from 10 C. to about 180 C.Suitable solvents for the reaction include ,chlorobenzene,o-dichlorobenzene, toluene and tetrachloroethane. The passage of thecarbonyl halide through the solution is normally continued for a periodof about 4 hours, or until reaction is complete. Isolation of theproduct may be effected easily by cooling the reaction mixture, underwhich conditions the phenolic carbamyl halide precipitates and may beremoved by filtration. Alternatively, the product may be precipitated bydilution of the reaction mixture with a suitable non-solvent. Amongsuitable N-substituted amino phenolic compounds from which thesecompounds may be prepared by reaction with phosgene may be named thefollowing: p-anilinophenol, m-anilinophenol, 1-anilino-3- naphthol,l-anilino-4-naphthol, 1-anilino5-naphthol, 2- anilino-6-naphthol, othersimilar N-substituted aminonaphthols, 4-anilino-4'-hydroxybiphenyl,3-anilino-3'-hydroxybiphenyl, 4-anilino-4-hydroxydiphenyl ether,4-anilino-4-hydroxydiphenyl sulfonate, 4-anilino-4'-hydroxydiphenylmethane, and other similar N-substituted aminophenols which mayadditionally bear one or more nuclear substituents of a non-urethaneforming type.

These polyurethanes may be prepared by various polymerizationtechniques. Melt polymerization may be utilized, Where the condensationof a substituted diamine with an aromatic bischloroformate iscontemplated. Suitable conditions for this procedure involve heating themixture to a temperature of C. for a period of 10 minutes for theinitial preparation of low polymer, and further heating the finelydivided product to a temperature of 200 C. for a period of 10 minutesfor its conversion to high molecular weight. Alternatively, the hightemperature solution technique described earlier may be utilized.Suitable solvents for this procedure include o-dichlorobenzene,chlorobenzene, toluene, tetrachloroethane, and various hydrocarbonsolvents, and the condensation may be effected at temperatures Withinthe range from about 50 to 300 C. Where the condensation reaction isbetween a carbamyl chloride group and a phenolic hydroxyl, a meltpolymerization may satisfactorily be employed. Thus, by heating thereactant or mixture of reactants to a temperature within the range ofbetween about C. to 250 C. for a period of from two to six hours, a highmolecular weight polymer results.

The stability of these polyurethanes is frequently improved by treatmentof the high molecular weight polymers with suitable monofunctionalcompounds to combine with the reactive end-groups of the polymer chain.This may be accomplished by treatment of the finished polymer with theselected monofunctional reagent, or by the introduction to thepolymerizing mixture of a measured small quantity of the monofunctionalcompound. Where the reactive end-groups of the polymer are of theN-substituted amine type, suitable monofunctional reactants includephenylchloroformate, acetic anhydride, benzoyl chloride, and other suchorganic compositions which are capable of reaction with the amino groupsby condensation. Where the polymer end-groups are of the phenolichydroxyl type, suitable monofunctional reactants include benzoylchloride, phenyl chloroformate, and other such organic compositionswhich are capable of reaction with the phenolic groups by condensation.Where the reactive end groups of the polymer are of the chloroformatetype, suitable monor'unctional reactants include phenol, ammonia,diphenylamine, aniline, other primary and secondary amines, and othersimilar organic compositions which are capable of reaction with thechloroformate end groups by condensation. When polymers are preparedfrom the reaction of difunctional reactants of the type which contain,in any one molecule, two similar reactive centers (as in the reaction ofa bischloroformate with an N,N-disubstituted aromatic diamine), the typeof end groups on the polymer chain may be controlled by the presence, inthe reaction mixture, of a small excess of one reactant. Thus, in thecase referred to above, a small excess of the diamine will produce apolymer having amine ends exclusively. Where polymer end groups are ofdifferent types (as from the self-condensation of the carbamyl chlorideof an N-substituted aminophenol), monofunctional reactants are so chosenthat they react by condensation with each type of end group. This isgenerally effected by utilizing two such monofunctional reactants, eachof which is capable of reaction with one of the end group types. Forexample, where the end groups are of the carbamyl halide and pehnolichydroxyl types, suitable pairs of monofunctional reactants includebenzoyl chloride and diphenylamine, acetic anhydride and phenol, and thelike. Treatment of the polymers with these monofunctional compositionsmay be effected in two stages, reacting the polymer first with one ofthe reagents and subsequently treating it with the second.Alternatively, it is frequently desirable to introduce to the polymerforming reaction mixture 2. small quantity of one of the monofunctionalreactants, thus forming a polymer having only one type of reactive endgroup. The final polymer can then be treated with the secondmonofunctional reactant to condense with the remaining type of endgroup. This procedure has the added advantage that it provide a means ofcontrolling the molecular weight of the final polymer.

Films, filaments, and other shaped articles comprising the polymers ofthis invention may be readily prepared either from solutions of thepolyurethanes in suitable solvent media, by melt shaping techniques, orby other recognized procedures. For the preparation of useful films andfibers, polymers having an inherent viscoity of at least 0.4 arenormally preferred. Where solutions are employed, it is desirable thatthey contain from about 15% to about of the polymer, and that theviscosity of the solution be between about 100 poises and 300 poises atthe temperature of shaping. Suitable solvents for such shapingprocedures include the following solvent media: 1,2,2- trichloroethane,sym-tetrachloroethane, dioxane, tetrahydrofuran, chloroform,N,N-dimethylformamide, dimethyl sulfoxide, methylene chloride, and othersolvents. Either dry-spinning or wet-spinning techniques may be employedfor the preparation of fibers comprising these polymers, but the formeris normally preferred. The fibers may be oriented by drawing, which canbe effected at room temperature or by the use of a hot pin at atemperature of up to about 180 C. resulting in an attenuation of 2X to 3Other drawing procedures may also be employed The melt shaping of thepolyurethanes of this invention may be accomplished by standardtechniques, and is generally the preferred method of shaping. For thisprocedure, it is desirable to utilize polymer having an inherentviscosity of greater than 0.30, and temperatures within the range of 200to 400 C. Some of the polymers may be satisfactorily utilized in shapedarticles even when inherent viscosities are lower than 0.30. Highspin-stretch ratios can be obtained, ranging as high as 600/1, or evenhigher. When this advantage is realized, exceptional fiber propertiesresult without further drawing.

Fibers of the polyurethanes of this invention may be woven to formfabrics which are characterized by excellent Wash-wear performance.Laundering by conventional means in commercially available machines maybe accomplished with ease, and the fabrics may be dried in automaticdriers or by hanging. There is no necessity, when automatic washingmachines are employed, for eliminating the spin drying which most ofthese machines utilize, or for drip-drying.

Although wash-wear performance of a polymer is best evaluated in testsunder actual use conditions on fabrics made from that polymer, usefulguides to such performance may be obtained from simple tests on fibers.Noteworthy among such tests are the tensile recovery, work recovery, andwash-set recovery angle.

The tensile recovery, or recovery from elongation, is expressed as thepercent return to the original length when a sample of fiber or yarn isstretched by a factor of 3 percent, for example. In this test the sampleis stretched at a rate of 10 percent of its test length per minute untilit has reached the desired elongation. The sample is held at thiselongation for 30 seconds, and then allowed to relax at a controlledrate of 10 percent per minute. The tensile recovery, expressed inpercent, indicates the extent to which the stretched fiber returns toits pre-stretched length.

The work recovery is a measure of the freedom from permanentre-alignment of the polymer molecules following stretching of a fiber oryarn sample of the polymer. The ratio, expressed in percent, of the workdone by the polymer molecules in attempting to return to their originalalignment following stretching to a pre-determined elongation to theWork done on the sample during stretching is termed the work recovery.The work recovery may be determined from the tensile recovery test graphwhich plots the tension on the sample against the elongation distance.The ratio, expressed as percent, of the area under the controlledrelaxation curve to the area under the stretching curve is the workrecovery.

The wash-set recovery angle is a measure of the ability of a fiber oryarn sample to return to its original shape after being wrapped around aWire while wet. The test is carried out as follows: The sample is bent360 around a 25 mil Wire mandrel and held in that condition under a loadequivalent to .05 gram per denier While being soaked for 2 minutes in a60 C. aqueous sodium sulfonate-type detergent solution. While stillunder tension, the sample is then rinsed with water at room temperature,and dried for 1 to 2 hours in a cabinet maintained at 21 C. and 13-15%relative humidity. The sample is then cut at both ends at a distance ofabout 0.5 inch from the mandrel, thus freeing it from the load weight.The sample is allowed to fall off the mandrel onto a fiat glass surfaceheld less than 2 inches away, and is stored at 21 C. and 13-15% relativehumidity for at least 16 hours. The extent to which the sample has thenreturned to its original linear shape is the wash-set recovery angle,expressed in degrees.

When sufficient fiber is available for Weaving into fabrics, it ispreferred to measure the actual wash-wear performance by launderingfabric samples at 55 C. in a home model automatic washin machine, usinga sodium sulfonate-type detergent, followed by tumble-drying at 68 C. inan automatic dryer. After removal from the dryer, the fabrics areallowed to hang for 1 hour or more, and are then evaluated by a group ofpersons who rate the wash-Wear performance on a scale of 0-5, 0indicating a badly wrinkled fabric that requires extensive ironing, 5

being a perfectly flat fabric having no evidence of wrinkling. Anintermediate value of 2, for example, is given to fabrics that requireonly little ironing to become flat.

The following examples illustrate this embodiment of the presentinvention by describing the preparation and shaping of the polyurethanesdisclosed herein. The examples are not intended to limit the inventionin any way. Inherent viscosities are determined in accordance with theformula previously given.

EXAMPLE XIII Commercially available N,N-diphenyl-p-phenylene diamine ispurified in accordance with Example I. The bischloroformate ofhydroquinone (prepared by phosgenation of hydroquinone in solution usingN,N-dimethy1- aniline as acid acceptor) is recrystallized from hexaneand further purified by distillation. To 265.5 grams ofN,N'-diphenyl-p-phenylene diamine and 235.0 grams of hydroquinonebischloroformate are added 2500 ml. of dry o-dichlorobenzene, and theresulting solution is heated over a period of 2 /2 hours to thetemperature of boiling. Throughout this period, and the subsequent threehours during which reflux is continued, the mixture is stirred andblanketed with nitrogen. To the solution are added 15 'ml. of phenylchloroformate, and reflux is continued with stirring for an additionalthree hours. Upon cooling the solution, the polymeric product isprecipitated, and it is removed by filtration, washed twice withacetone, and dried in an evacuated oven at a temperature of 140 C. Afterfurther drying at a temperature of 240-250 C. under high vacuum, thepolymer is found to have an inherent viscosity of 0.49 in sulfuric acid,a second-order transition temperature of 185 C., a melt temperature of290 C., and has a linear arrangement of repeat units having thefollowing structure:

Polyurethane prepared as described in the preceding paragraph ismelt-spun at 5400 p.s.i. through a S-hole spinneret having .007-inchorifices. The spinneret is maintained at 299 C., and the yarn is woundup at 400 feet per minute. The yarn denier per filament is 2.3. Thesefibers exhibit a tenacity/elongation/modulus ratio of 3.6/22/42, atensile recovery of 96% at 3% elongation, a work recovery of 86% at 3%elongation, and a washset recovery angle of 300. Under the same testconditions commercial poly(ethylene terephthalate) continuous filamentexhibits a tensile recovery of 81%, a work recovery of 42%, and awash-set recovery angle of 210.

The polyurethane, prepared as described in the first paragraph of thisexample, is dry-spun as a 17.5% solution in a 2.5/1 mixture of1,1,2-trichloroethane/formic acid. A spinneret having 17 orifices, each.004 inch in diameter, is operated at 65 C. and 135 p.s.i. Air at 130 C.flows through the spinning cell at 5 cubic feet per minute, and the yarnis wound up at a rate of 133 yards per minute. The rate of extrusion ofthe polyurethane solution through the spinneret is about 6.5 ml. perminute. The yarn is then drawn over a pin held at 85 C. to 1.8 times itsinitial length, given a 7 Z twist, and woven into a 118 x 85 counttaffeta fabric. The fabric is then heat-set at 140 C., allowing about 5%shrinkage in each direction. The heat set fabric exhibits 77% recoveryfrom creasing at 40 C. While Wet. Under the same conditions a similarfabric Woven from commercial poly(ethylene terephthalate) recovers tothe extent of 65%. The crease-recovery test used for these measurementsis ASTM D1295-53T, modified to the exsteps in place of the standardS-minute periods. This crease-recovery test indicates that thepolyurethane gives more satisfactory performance as a Wash-wear fiberthan commercial poly(ethylene terephthalate).

Further evidence of the superior properties of the polyurethane as awash-Wear fiber is provided in the standard laundering test describedhereinabove. The taffeta fabric exhibits a wash-wear rating of 4.7, whenallowed to hang for 2 hours following the tumble-drying step. Under thesame conditions a fabric made from commercial poly- (ethyleneterephthalate) has a rating of about 2.

By the procedure described in Example III, it is found that thispolyurethane loses 7.7% of its initial weight when heated to 459 C.under nitrogen. Under the same test conditions, the analogousunsubstituted polyurethane, poly(p-phenylene p-phenylenedicarbamate) ofsubstantially the same molecular weight loses 64.9% of its initialweight, and poly(p-phenylene N,N-dimethyl-p-phenylenedicarbamate) losesin excess of 25% of its initial weight.

The hydrolytic stability is also determined by the method described inExample III, and it is thereby found that the poly(p-phenyleneN,N'-diphenyl-p-phenylenedicarbamate) loses 4.5% of its initial weight.When subjected to the same test, poly(p-phenylenep-phenylenedicarbamate) loses of its initial weight.

The above-mentioned unsubstituted polyurethane may be prepared by theroom temperature reaction between equimolar quantities of hydroquinoneand p-phenylene diisocyanate in a 5% solution of lithium chloride inN,N-dimethylformamide. The N,N-dimethyl and other dialkyl derivativesmay be made from hydroquinone bischloroformate and the appropriateN,N'-dialkyl-p-phenylenediamine in the presence of an acid-acceptor bythe general procedures disclosed in U.S. Patents 2,731,445 and2,973,333.

EXAMPLE XIV The polyurethane derived from N,N'-diphenyl-p-phenylenediamine and hydroquinone bischloroformate may also be prepared by a meltpolymerization. To 26.03 grams of the pure diamine and 23.50 grams ofthe pure bischloroformate are added 300 ml. of methylene chloride. Uponwarming the mixture, a solution is obtained, and the solvent ispermitted to boil off. Heating on a steam bath is continued for a periodof 10 minutes, when the reaction mixture has been converted to a solidcolorless low polymer having an inherent viscosity of 0.12. This polymeris finely powdered and heated for ten minutes to one hour at atemperature of 196 C. Reduced pressure may be employed for all or aportion of the reaction period. The product has an inherent viscosity of0.56 and the structure indicated in Example XIII. High molecular weightpolymer is also obtained by heating the powder in air at a temperatureof 200 C. for a period of ten minutes.

EXAMPLE XV In a three-necked, round-bottom flask equipped with anitrogen inlet, reflux condenser, and stirrer are placed 14.00 grams(0.054 mol) of N,N-diphenylp-phenylenediamine (twice recrystallized frommethylene chloride), 19.00 grams (0.054 mol) of freshly distilled2,2-bis(4- hydroxyphenyl) propane bischloroformate, and 250 ml. ofdistilled and dried o-dichlorobenzene. The mixture is heated by means ofan oil bath to the temperature of reflux until the evolution of hydrogenchloride has ceased. This requires approximately three hours, duringwhich the mixture is stirred and maintained in a nitrogen atmosphere.The mixture is permitted to cool to room temperature and the polymer isprecipitated with cyclohexane in a blendor. The product is isolated byfiltration, washed with cyclohexane, and dried overnight in an evacuatedoven under nitrogen. Polymerization is continued by heating the drypowdered material at a temperature of 196 C. under reduced pressure fora period of two hours. The polymer is found to exhibit a melttemperature of 290 C. and an 17 inherent viscosity of 0.33. Tough filmsare prepared by melt pressing at a pressure of 8,000 p.s.i. and attemperatures ranging from 250 C. to 400 C. Films are also dry cast fromcyclohexanone and found to be tough and creasable. The polymer has alinear arrangement of repeat units having the following structure:

Polymer prepared as described in the preceding paragraph is made intofibers by dry-spinning from a 15% solution in dioxane at a rate of 2.9ml. per minute through a spinneret having orifices each .005 inch indiameter, using a pressure of 110 p.s.i. The spinneret temperature is 75C., and the cell air temperature is 132 C. The yarn is wound up at 135yards per minute, and is subsequently dried in a vacuum oven to removeadditional solvent. After drawing to about 2 times the dried length overa pin at 100-410 C., the yarn exhibits a tenacity/elongation/modulusratio of 1.6/37/ 30, a tensile recovery of 90% at 3% elongation, a workrecovery of 79% at 3% elongation, and a wash-set recovery angle of 295.These properties are indicative of wash-wear performance superior tothat of commercial poly(ethylene terephthalate) EXAMPLE XVI By aprocedure analogous with those previously described, 14.00 grams (0.054mol) of twice-recrystallized N,N'-diphenyl-p-phenylenediamine, 16.74grams (0.054 mol) of 4,4'-dihydroxydiphenyl bischloroformate, and 250ml. of distilled and dried o-dichlorobenzene are placed in a reactionflask. The mixture is heated by means of an oil bath to the temperatureof reflux, and this temperature is maintained for a period of 5 hours,at which time no additional hydrogen chloride is being evolved. Aftercooling the mixture to room temperature, the product is precipitatedwith acetone in a blendor, isolated by filtration, washed twice withacetone in the blendor, filtered and dried overnight in an evacuatedoven at a temperature of 80 C. while a nitrogen atmosphere is imposed.Polymerization is furthered by heating the powdered polymer at atemperature of 256 C., for a period of two hours under reduced pressure.The resulting polymer is melt pressed into tough films at a temperatureof 350 C.

and a pressure of 8,000 p.s.i. The polymer is found to pos- P sess aninherent viscosity of 0.81 and a polymer melt temperature of 320 C. Thepolymer repeat unit has the following structure:

I it i :1

The polymer is dry-spun from a 17% solution in 1,1,2- trichloroethane,using a 5-hole spinneret having .005 inch orifices. The solution issupplied to the spinneret at 58 C. and at a rate of 2.9 ml. per minute.The air in the cell is held at 125 C. and the yarn is Wound up at 126yards per minute. The yarn is drawn to 2.1 times its length in p.s.i.steam, and then exhibits a tenacity/elongation/mod- 18 ulus ratio of3.3/ 40/41, a tensile recovery of 87% at 3% elongation, a Work recoveryof 64% at 3% elongation, and a wash-set recovery angle of 290.

EXAMPLE XVII A three-necked, round-bottom flask equipped with a nitrogeninlet, a stirrer, and a reflux condenser, is charged with 6.73 grams(0.020 mol) of N,N'-dipheny1benzidine, 4.70 grams (0.020 mol) of freshlydistilled hydroquinone bis-chloroformate, and 100 ml. of distilled anddried o-dichlorobenzene. The mixture is heated to the temperature ofreflux while stirring and maintained in a nitrogen atmosphere underthese conditions for a period of one hour. No hydrogen chloride gas isbeing evolved after that time. The mixture is permitted to stand at roomtemperature overnight, and the product is precipitated with cyclohexanein a blendor. The polymer is isolated by filtration, washed twice withadditional portions of cyclohexane in a blendor, refiltered, and driedfor six hours in an evacuated oven at a temperature of approximately 70C. A very tough film is cast from a solution comprising 3 grams of thepolymer in 15 ml. of 1,1,2-trichloroethane. The polymer exhibits aninherent viscosity of 0.76 (when measured in 1,1,2-trichloroethane), andrepeat units having the following structure:

EXAMPLE XVIII A mixture comprising 6.73 grams (0.020 mol) of N,N-diphenylbenzidine, 7.06 grams (0.020 mol) of freshly distilled2,2-bis(4-hydroxyphenyl) propane bischloroformate, and 100 m1. ofdistilled and dried o-dichlorobenzene is heated in a nitrogen atmospherewith stirring to the temperature of reflux for a period of one hour. Theevolution of hydrogen chloride has ceased at the completion of thisperiod. The mixture is cooled to room temperature, and the product isprecipitated by treatment of the mixture with cyclohexane in a blendor.After being twice washed with cyclohexane, the polymer is isolated byfiltration and dried in an evacuated oven overnight at a temperature ofC. Tough films are cast from solutions of the polymer in1,1,2-trichloroethane. The polymer exhibits an inherent viscosity of0.51 (when measured in 1,1,2-trichloroethane) and a polymer melttemperature of 270 C., and comprises repeat units having the followingstructure:

EXAMPLE XIX In a three-necked, round-bottom flask are placed 21.00 grams(0.081 mol) of freshly recrystallized N,N'-diphenyl-p-phenylenediamine,18.98 grams (0.081 mol) of redistilled resorcinol bischloroformate, and250 ml. of dry o-dichlorobenzene. The mixture is heated while in anitrogen atmosphere to the temperature of reflux and maintained withstirring at that temperature until the evolution of hydrogen chloridehas ceased, this being accomplished in about one hour. The polymer isprecipitated by treatment with cyclohexane in a blendor, further washedwith cyclohexane, isolated by filtration, and dried overnight in anevacuated oven at a temperature of 70 C.

Further powder polymerization is effected by heating the polymer at atemperature of 100 C. under reduced pressure for a period of two hours.The polymer exhibits a melt temperature of 164 C., an inherent viscosityof 0.12, and comprises repeat units having the following structure:

Q NQZOG EXAMPLE XX By a procedure analogous with those previouslydescribed, 2.60 grams (0.010 mol) of N,N'-diphenyl-pphenylenediamine,4.91 grams (0.010 mol) of 4,4-isopropylidene bis(2,6-dichlorophenylchloroformate), and 90 ml. of dry o-dichlorobenzene are heated togetherat the temperature of reflux with stirring for a period of hours. Uponcooling to room temperature, the polymer remains soluble in solution,and the mixture is treated with cyclohexane in a blendor. The product isremoved by filtration and dried overnight in an evacuated oven at atemperature of 75 C. It is further powder polymerized for a period oftwo hours at a temperature of 196 C. under reduced pressure, followingwhich it exhibits an inherent viscosity of 0.10 (when measured in1,1,2-trichloroethane), and a polymer melt temperature of 230 C. Thispolymer is a polyurethane having repeat units with the followingstructure:

EXAMPLE XXI In a polymer tube equipped with a capillary nitrogen inletare placed 20 grams (0.08 mol) of N-chlorocarbonyl-p-anilinophenol. Thetube and its contents are heated to a temperature of 190 C. andmaintained at that temperature for a period of 15 minutes while areduced pressure of mm. is imposed. The pressure is then reduced to 1.0mm. and the temperature is kept at its former level for a period of 1%hours, following which the temperature is raised to 245 C. while thepressure is maintained at 1.0 mm. for an additional three hours.Polymerization occurs rapidly under these conditions, and the polymer isremoved from the tube by dissolving in methylene chloride. Precipitationof the product is effected by treatment of the solution with methanol,following which the polymer is isolated by filtration, washed and dried.It is found to exhibit a polymer melt temperature of 256 C. and aninherent viscosity, when measured in m-cresol, of 0.6. Tough films areprepared by melt-pressing or by casting from solution. This polymer is apolyurethane in which the repeat unit has the following structure:

EXAMPLE XXII A solution comprising 6.73 grams (0.02 mol) of N,N'-diphenylbenzidine and 6.22 grams (0.02 mol) of 4,4'-biphenylenebischloroformate dissolved in 100 ml. of dry o-dichlorobenzene is heatedto the temperature of reflux and maintained at that temperature withstirring for a period of one hour, by which time no additional hydrogenchloride is being evolved. The polymeric product is isolated byprecipitation with cyclohexane in a blendor and is twice washed withcyclohexane and dried. The polyurethane exhibits an inherent viscosityof 0.94 when measured in 1,1,2-trichloroethane and a polymer melttemperature of 350 C. A portion of the polymer is dissolved in1,1,2-trichloroethane to form a solution containing approximately 10%solids and a clear, tough film is cast. The film is tough and creasableeven after heating at a temperature of 275 C. for a period of fifteendays in air. The polyurethane comprises repeat units having thefollowing structure:

EXAMPLE XXIII Equivalent qualities of p-anilinophenol and thecloroformate of thiophenol are dissolved in chlorobenzene and heated toa temperature of C. The resulting product melts at a temperature of C.,exhibits an elemental analysis corresponding to C H NO S, and ischaracterized by infrared spectral analysis as the urethane having thestructure:

A 2.5 gram portion of the above urethane is heated with 0.02 gram oftributyl tin acetate for a period of three hours at a temperature of 225C. in a nitrogen atmosphere, and for a further period of sixteen hoursat the same temperature and at a pressure of 1 mm, Thiophenol iseliminated under these conditions and a viscous melt of thecorresponding N-substituted polyurethane results. Heating is continuedfor an additional period of four hours at a temperature of 278 C. and ata pressure of 1 mm. to further polymerize the composition. The resultantpolymer exhibits an inherent viscosity (measured in cresol) of 0.3, apolymer melt temperature of 250 C., an ability to be converted to fibersfrom the melt, and possesses the structure shown in Example XXI.

EXAMPLE XXIV The procedure described by Craig in the Journal of theAmerican Chemical Society, vol. 55, pages 3723-7 (1933), is used toprepare p,p'-dianilinodiphenylmethane, B.P. 268-273 C. at 0.40 mm.mercury. The product is purified by recrystallization from ethyl alcoholafter decolorization with activated charcoal, and then melts at 122-123C. The composition found by elemental analysis corresponds to theformula, C H N A solution is made by warming a mixture of 10.51 g. (0.03mole) p,p'-dianilinodiphenylmethane and 90 ml. chlorobenzene, To thissolution, maintained under a nitrogen atmosphere, is added a solution of7.05 g. (0.03 mole) of hydroquinone bischloroformate. The mixture isthen heated to its boiling point, and is stirred under reflux for 23hours. Hydrogen chloride is evolved, and part of the polymerprecipitates out. The pale yellow mixture is allowed to stand at roomtemperature for-1 day; a small amount of solid polymer separates fromthe mixture. The mixture is poured into petroleum ether to precipitateadditional polymer. The polymer is removed by filtration, washed withacetone and ethyl alcohol, and dried at 70,

Fibers are dry-spun from polymer =1.24) prepared as described above,using a 25% solution in dimethylformamide. A spinneret with holes, each.005 inch in diameter, is used at 122 C.; the air in the spinning cellis at 166-209 C. The fibers are wound up at a rate of 137 yards perminute, combined into a fifteenfilament yarn, soaked overnight in water,drawn 2X in p.s i. steam, and heat-set for 30 minutes in p.s.i. steam.After a -minute boil-0E, washing, and drying, the fibers exhibit atenacity/elongation/modulus ratio of 2.1/ 49/ 30, a tensile recovery of95% at 3% elongation, a work recovery of 83% at 3% elongation, andWash-set recovery angles in the range of 300320.

EXAMPLE XXV The procedure described by Craig in the Journal of theAmerican Chemical Society, vol. 60, pages 1458- 1465 (1938) is used toprepare p,p'-dianilinodiphenylpropane from acetone and diphenylamine.The product is isolated by distillation at 280-283 C. at 0.35 mm.mercury, treated with activated charcoal, and recrystallized from ethylalcohol to give a solid that melts at 90100 C.

A solution of 3.785 g. (0.01 mole) p.p'-dianilinodiphenylpropane in 30ml. chlorobenzene is mixed with a second solution prepared from 3.532 g.(0.01 mole) of the bischloroformate of p,p'-diphenylolpropane and 30 ml,chlorobenzene. Nitrogen is bubbled slowly through the mixture while themixture is heated at 115 130 C. under reflux for one day. The yellowsolution is cooled and poured into ethyl alcohol to precipitate thesolid polyurethane, which is removed by filtration, washed with alcoholand petroleum ether, and dried at 75 C. in vacuo. The dried whitepolymer weighs 6.54 g., exhibits a polymer melt temperature of 360 C.and an inherent viscosity of 0.64 in m-cresol, Tough, flexible films arecast from solutions of the polymer in chloroform. The repeat unit in thepolymer has the structure:

and phenol; films are made by pressing at 345 C. The polymer comprisesrepeat units having the structure:

i it O Polyureas The polyureas of this invention are, like the otherpolymer types, characterized by high levels of resistance to thermal andhydrolytic degradation, and by the presence in the polymeric chain ofamide-like linkages, the nitrogen atoms of which bear monovalentaromatic substituents of the types to which reference has previouslybeen made. The polyureas are also characterized by their ability to beconverted to fibers and films.

These polyureas are prepared from N,N'-disubstituted aromatic diaminesby condensation with the biscarbamyl halides of similarN,N-disubstituted aromatic diamines. The diamines of utility in thepreparation of these polymers have the following formula:

wherein Ar and R have the meanings previously given. Among suitablediamines of this type may be named the following:N,N-diphenyl-p-phenylenediamine, N,N-diphenyl-m-phenylenediamine,N,N-diphenyl-l,4naphthylenediarnine,N,N'-diphenyl-1,3-naphthylenediamine, N,N- diphenyl 2,6naphthylenediamine, N,N' diphenyl 1,5- naphthylenediamine,N,N'-diphenylbenzidine, and the like. Any of the above-namedN,N'-disubstituted aromatic diamines may be converted to thecorresponding biscarbamyl halides by reaction with phosgene or withcarbonyl bromide in accordance with known procedures.

The preparation of high molecular weight polyureas may be effected bydissolving equivalent amounts of the diamine and the biscarbamyl halideor the biscarbamate ester in a suitable solvent having a boiling pointin the range of 350 C. Upon maintaining the solution at the temperatureof reflux for a period of 5-20 hours, a high molecular weight product isformed. Hydrogen chlo ride produced as a by-product of the condensationis volatilized under the conditions of reaction. The polymeric EXAMPLEXXVI Commercially available 2,S-ditertiarybutylhydroquinone is convertedto its bischloroformate by reaction with excess phosgene. Thebischloroformate boils at 143149 C. at 0.8 mm. mercury, and isrecrystallized from n-hexane to give crystals that melt at l23l24 C. andanalyze correctly for the formula C H O Cl A polyurethane is preparedfrom the above mentioned bischloroformate (6.97 g., 0.02 mole) andN,N-diphenylpphenylenediamine (5.20 g., 0.02 mole) in 120 ml.o-dichlorobenzene at reflux for 46 hours. The clear yellow solution iscooled and poured into petroleum ether to precipitate the polyurethane,which is removed by filtration, washed with petroleum ether, and driedat C. in vacuo to give the polymer in the form of a gray-white solid.The polymer melt temperature is 344 C., and the inherent viscosity is0.43 in a mixture of trichloroethane product may normally be isolated bycooling the reaction mixture and filtering the precipitated polymer. Inthose instances where the polymer remains soluble in the cooled reactionmixture, it may be isolated by dilution of the mixture with a suitablenon-solvent. Suitable solvents for effecting solution polymerization aregenerally chosen from the class of hydrocarbons and chlorinatedhydrocarbons, as chlorobenzene, o-dichlorobenzene, toluene, xylene,tetrachloroethane, and the like. Particularly preferred iso-dichlorobenzene, whose temperature of reflux permits rapidpolycondensation.

Polyureas prepared by the above techniques may be utilized directly inthe formation of shaped articles, which may be prepared from solutionsof the polymers in suitable solvents, by melt shaping, or by otherrecognized procedures. The spinning of fibers from solution may beaccomplished either by dry-spinning or by wet-spinning techniques,although the former is preferred. Suitable solvents include methylenechloride, 1,1,2-trichloroethane, tetrachloroethane, mixtures of1,1,2-trichloroethane and trifluoroacetic acid, and the like, andspinning solutions normally contain between 12 and 25% of the polymer.Such solutions have viscosities within the range of 100300 poises at thespinning temperature. Dry-spinning may be accomplished in accordancewith accepted procedures, and the resulting fibers may be drawn andoriented by conventional techniques.

The following example illustrates the preparation and properties of apolyurea of this invention. It is not intended to limit the invention inany manner.

EXAMPLE XXVII A solution comprising 150 grams (0.577 mol) of distilledand recrystallized N,N-diphenyl-p-phenylenediamine in 1200 ml. of dryo-dichlorobenzene is heated to a temperature of 130 C., and maintainedat that temperature for a period of four hours while phosgene is bubbledthrough the solution. The reaction mixture is cooled and the biscarbamylchloride is removed by filtration, washed, dried, and recrystallizedfrom o-dichlorobenzene. A portion of the biscarbamyl chloride isconverted to the corresponding biscarbamyl bromide by heating a mixtureof 40 grams (0.104 mol) of the former with 300 grams (1.107 mol) ofphosphorus tribromide, and maintaining the mixture at the temperature ofrefiux with stirring for a period of two hours. The mixture is cooled byimmersion of the flask in an ice bath, the product is removed byfiltration, washed, dried, and recrystallized from o-dichlorobenzene. A9.48 gram (0.02 mol) portion of the biscarbamyl bromide is dissolvedtogether with 5.20 grams (0.02 mol) of distilled and recrystallizedN,N'-diphenyl-pphenylenediamine in 125 ml. of dry o-dichlorobenzene. Themixture is heated to the temperature of reflux and maintained at thattemperature with stirring for a period of 24 hours. After cooling, theproduct is precipitated by dilution of the reaction mixture with hexanein a blendor. The low polymeric product is separated by filtration,washed, and dried. Further polymerization is effected by heating theproduct under reduced pressure for a period of two hours at atemperature of 256 C. The resulting polyurea exhibits an inherentviscosity, when measured in sulfuric acid, of 0.28, and a melting pointof 266 C. Fibers of the polymer can be manually spun from the melt. Thispolyurea has a structure comprising repeat units corresponding to theformula:

What is claimed is: 1. A fiber-forming nitrogen-containing linearcondensation polymer consisting essentially of recurring structuralunits of one of the following:

wherein R is phenyl which may be substituted with lower alkyl, halogenor p-phenyl radicals and Ar and R are selected from the group consistingof phenylene, naphthylene, biphenylene, alkylene diphenylene, sulfonyldiphenylene, oxy diphenylene and the haloand lower alkyl ringsubstitutedderivatives thereof; and n is a cordinal number not greater than 1.

2. A fiber-forming nitrogen-containing linear condensation polymerconsisting essentially of a plurality of the following recurringstructural units:

II II References Cited UNITED STATES PATENTS 2,149,286 3/1939 Graves260-78 2,158,064 5/1939 Carothers 26078 3,232,910 2/1966 Preston 260783,264,270 8/1966 McIntyre 26078 3,094,511 6/1963 Hill et al 260783,164,571 1/1965 Cotter 26077.5

WILLIAM H. SHORT, Primary Examiner.

H. D. ANDERSON, Assistant Examiner.

U.S. C1. X.R.

1. A FIBER-FORMING NITROGEN-CONTAINING LINEAR CONDENSATION POLYMERCONSISTING ESSENTIALLY OF RECURRING STRUCTURAL UNITS OF ONE OF THEFOLLOWING: